'Agkistrognathus belongs to Thalattosaurida' according to E. L. Nicholls 1999'Askeptosaurus belongs to Thalattosauriformes' according to E. L. Nicholls 1999'Clarazia belongs to Thalattosauridae' according to E. L. Nicholls 1999'Diapsida belongs to Reptilia' according to E. L. Nicholls 1999'Endennasaurus belongs to Thalattosauriformes' according to E. L. Nicholls 1999'Hescheleria belongs to Thalattosauria' according to E. L. Nicholls 1999'Nectosaurus halius belongs to Nectosaurus' according to E. L. Nicholls 1999'Nectosaurus belongs to Thalattosauroidea' according to E. L. Nicholls 1999'Paralonectes belongs to Thalattosaurida' according to E. L. Nicholls 1999'Thalattosauria belongs to Thalattosauriformes' according to E. L. Nicholls 1999'Thalattosaurida belongs to Thalattosauridae' according to E. L. Nicholls 1999'Thalattosauridae belongs to Thalattosauroidea' according to E. L. Nicholls 1999'Thalattosauriformes belongs to Diapsida' according to E. L. Nicholls 1999'Thalattosauroidea belongs to Thalattosauria' according to E. L. Nicholls 1999'Thalattosaurus alexandrae belongs to Thalattosaurus' according to E. L. Nicholls 1999'Thalattosaurus borealis belongs to Thalattosaurus' according to E. L. Nicholls 1999'Thalattosaurus perrini is a nomen dubium' according to E. L. Nicholls 1999'Thalattosaurus shastensis is a nomen dubium' according to E. L. Nicholls 1999'Thalattosaurus belongs to Thalattosaurida' according to E. L. Nicholls 1999